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. 2021 Sep 9;24(10):103108. doi: 10.1016/j.isci.2021.103108

Figure 1.

Figure 1

Levels of glutamate metabolic proteins are not uniformly increased after TBI

(A) Enzymes and metabolites involved in glutamate handling. Glutamate can be decarboxylated to form GABA, aminated to glutamine or transaminated to form alpha-ketoglutarate. Under homeostatic conditions in the brain, the conversion of glutamate to glutamine is the predominant reaction in astrocytes (bold arrow).

(B and C) The protein fold change ratios for TBI/Sham animals, derived from the cortex or hippocampus, from a parallel proteomics study at (B) 24 h and (C) 2 weeks for enzymes related to glutamate metabolism. Each data point represents a value from a different animal (4 animals in total). Red symbols represent statistically significant fold changes for that protein. Black symbols represent proteins that were confidently identified but did not have a statistically significant fold change. Gfap is shown to illustrate that the animals were injured and that the brain has elicited a consistent response to TBI among the majority of animals. Overall, no consistent change was observed for glutamate metabolizing enzymes at 24 h or 2 weeks in the cortex and hippocampus. In the cortex at 24 h, Glutamate decarboxylase 2 (GAD2) was increased in one animal. Glutamine synthase (Glns) was significantly increased in two of four injured animals, and glutamate dehydrogenase (Gdh) was decreased significantly in two. Aspartate aminotransferase 1 (Got1) was increased in one animal and decreased in another. The branched chain aminotransferase 1 (Bcat1) and 4-aminobutyrate aminotransferase (Abat1) were both reduced in animal 145. Glutamate decarboxylase 1 (GAD1), Aspartate aminotransferase 2 (Got2) and Phosphoserine aminotransferase (Psat1) were all unchanged. In the hippocampus at 24 h, GAD1 and GAD2 were both increased in an animal. Glns was increased in one animal and decreased in another. Got2 and Abat1 were each decreased in an animal. Gdh, Got2, Bcat1 and Psat1 were unchanged. At 2 weeks in the cortex, GAD2 and Glns were each increased in an animal and Gdh was decreased in one animal. At 2 weeks in the hippocampus, the only change observed was to Glns in one animal.